(1) Field of the Invention
The present invention pertains to a row former that is part of a conveying system that receives a number of objects conveyed by the conveying system and arranges the number of objects received in a row, and then positions sequentially arranged rows of the objects side by side forming a two dimensional array of the objects. In particular, the present invention pertains to a novel row former that is designed to prevent relative movement between objects arranged in a row and being positioned by the row former adjacent a previously arranged row, where the objects have uneven or irregular cross section widths.
(2) Description of the Related Art
Conveying systems for conveying objects, for example lightweight blow molded plastic bottles, typically include portions of the conveying system that quickly convey one or more single file streams of the objects from one station of the conveying system to another station, for example from a blow molding station where plastic bottles are formed to a downstream palletizing station where the blow molded bottles are arranged on pallets. Conveying systems also often include row forming conveyors that receive objects from the one or more single file streams of conveyed objects, arrange predetermined numbers of the objects in rows and position the rows side by side on a row accumulating table forming two dimensional arrays of the objects. Forming the objects in the two dimensional arrays is usually done prior to palletizing of the arrayed objects in stacked layers, for example in cartons, on sheets or on pallets that are later wrapped in shrink wrap or bound.
The typical row forming conveyor is comprised of a conveyor belt on which numbers of the conveyed objects are arranged in rows and then positioned side by side on the accumulating table in forming the two dimensional arrays of the objects. The typical row forming conveyor also includes a row former that receives a number of objects from the stream of objects conveyed to the row forming conveyor and arranges a number of objects in a row and then positions sequentially arranged rows of objects side by side on the accumulating table in forming the two dimensional array.
The row former includes a pair of spaced, parallel arms that define a row forming slot between the arms. The arms are positioned above the row forming conveyor where the slot between the arms receives a number of objects from the stream of objects conveyed by the row forming conveyor between the slot of the arms. The arms arrange the number of objects received in the slot in a row between the arms. With the number of objects filling the slot of the row former, the conveyed stream of objects is held back by a gate and the row former with the arranged row of objects moves in a direction perpendicular to the row a short distance across the row forming conveyor and onto a surface of the accumulating table. The arms of the row former then stop and move vertically upward from the accumulating table surface, leaving the number of objects in the first arranged row on the accumulating table surface.
The pair of row former arms are then moved in the opposite direction across the row accumulating table surface back to their position in line with the conveyor conveying the stream of objects to the row forming conveyor. The arms are then moved vertically downward aligning the slot between the pair of arms again with the conveyor conveying the stream of objects. The gates of the conveyor are opened and the slot between the row former arms is again filled with a number of objects, upon which the gates of the conveyor are closed. The pair of arms with the number of objects arranged in the second row between the arms are then moved a short distance across the row forming conveyor and onto the surface of the row accumulating table, positioning the second arranged row adjacent the first arranged row of objects. As the pair of arms is moved across the row forming conveyor surface moving the second arranged row of objects a sufficient distance to clear the position the row former occupies when it receives the number of objects from the conveyor, the forward most arm of the row former pushes the first arranged row of objects in front of the forward most arm, sliding the first arranged row of objects a short distance across the row accumulating table. Once the area of the row forming conveyor that the pair of arms occupy when receiving the number of objects from the conveyor is cleared, the pair of row former arms are again moved upwardly leaving the second arranged row of objects adjacent the first arranged row of objects. The arms then move back over the row forming conveyor to their positions where they will receive the next number of objects arranged in a row in the slot between the row forming arms. The sequence of movements of the row former arms are repeated with previously arranged rows of objects being pushed across the row accumulating table surface by subsequently arranged rows of objects that are in turn pushed across the row accumulating table surface by the movement of the forward most forming arm, thereby positioning rows of numbers of objects side by side in forming a two dimensional array of the objects on the row accumulating table surface.
Prior art row accumulating tables have worked well in arranging numbers of objects in rows and then positioning the rows side by side in forming a two dimensional array of the objects where the objects being formed in the array are symmetric about their center vertical axes. Plastic blow molded bottles that are symmetric about their center vertical axes that pass through the centers of the bottle necks are examples of such objects. With each of the individual objects or bottles in an arranged row being symmetric about its center vertical axis, it did not matter if the object was rotated or caused to move slightly about its center axis as the row former forward arm pushed the row of objects across the row forming conveyor and onto the row accumulating table surface because the relative orientations of the bottles in the pushed row and in the previously positioned rows on the row accumulating table surface would remain unchanged.
However, difficulties were encountered in positioning rows of plastic blow molded bottles side by side in forming two dimensional arrays when the shapes of the bottles changed from the conventional shape symmetric about its center axis, to an asymmetric shape having an uneven width dimension across a cross section of the bottle. For example, blow molded plastic bottle designs were developed having general trapezoidal shaped cross sections, with handles formed as pinched in indentations at one side of the bottles. Forming a bottle in this shape would result in the bottle having a cross section that is narrower at one side of the bottle, the side formed with the pinched in handle indentations, than at its opposite side. Bottles molded with these configurations, when arranged by a row former in a row with the narrower sides of the bottles abutting against the wider sides of adjacent bottles, would at times rotate or move about the center vertical axes of the bottle necks when the forward arm of the row former would push the arranged row of bottles across the row accumulating table surface. This would result in one or more of the bottles positioned in the side by side rows of bottles of the two dimensional array being rotated or moved slightly relative to the other bottles of the same row or adjacent rows, which would ultimately create problems in the palletizing of the two dimensional array of bottles in a carton or on a pallet.
To overcome this problem, a mechanism is needed that prevents the relative movement of bottles having uneven cross section widths as rows of the bottles are positioned side by side by a row former in forming a two dimensional array of the bottles on a row accumulating table surface.
The present invention overcomes the disadvantages associated with prior art row formers by providing a row former having an arm with a plurality of protrusions that engage with the narrower width portions of bottles previously arranged in a row by the row former on the row accumulating table and prevent relative movement between the bottles of the row as the arm pushes sequential rows of bottles across the surface of the row accumulating table.
The row former of the present invention employs several features of row formers of the prior art, and additional novel features that enable the row former to move rows of irregularly shaped objects (or objects having uneven widths across their cross sections) across a row forming conveyor surface and onto a row accumulating table while preventing relative disorienting movement of objects in a previously arranged row that have been pushed onto the row accumulating table surface. The row former works in conjunction with a row accumulating table having a flat, planer surface on which rows of objects are arranged and positioned side by side in forming a two dimensional array of the objects. The formed array of objects are then typically packaged in layers in a carton, on a sheet or on a pallet.
In the preferred embodiment of the invention the row former comprises at least two row former arms or blades that are positioned side by side with a spacing slot between the parallel arms. The dimension or width of the spacing slot is determined to be slightly larger than the cross section width of the row of objects to be arranged in the slot by the row forming conveyor and then moved across the row forming conveyor and onto the row accumulating table surface. A frame holds the pair of arms in their spaced positions. An opening is provided at one end of the pair of arms and an end wall is secured between the arms at the opposite end of the pair of arms. The opening provides access into the slot between the pair of arms for a row of objects to be conveyed into the slot. The end wall at the opposite end of the arms is positioned to be engaged by the row of objects conveyed into the slot preventing the objects from exiting the opposite end of the slot and providing a reference edge for the number of objects received in the slot.
The frame of the pair of arms is operatively connected to a first drive mechanism of the row forming conveyor. The first drive mechanism selectively moves the pair of arms in a direction transverse to the lengths of the arms across the top surface of the row forming conveyor to move a row of objects across the conveyor surface. A second drive mechanism then moves the pair of arms vertically upward to a position above the row of objects where the pair of arms can then be moved horizontally back and vertically downward to the original position the arms occupied when filled with the row of objects.
The row of objects received between the pair of arms are held against relative movement by their engagement with the pair of arms and their engagement with each other as the pair of arms push the row of objects across the row forming conveyor. The leading arm of the pair of arms that is positioned in front of the row of objects pushed by the arms is provided with a plurality of protrusions. The protrusions are positioned on the downstream side of the leading arm from the slot where they each will engage with the narrower width portions of the previously arranged row of objects adjacent the arm. The protrusions are positioned in a spatial arrangement along the length of the arm and are given a predetermined length projecting from the arm. The larger width portions of the objects in the previously arranged row engage with the arm while the narrower width portions of the objects engage with the protrusions as the leading arm is swept over the row accumulating table surface pushing the row of objects before it toward the array of objects being formed on the row accumulating table surface. In the preferred embodiment, the protrusions are a plurality of pins that cantilever from the leading arm adjacent its bottom edge. The longitudinal spacing between adjacent pins is determined by a longitudinal width dimension of the objects in the row, and the extension of the pins from the leading arm is determined by the difference in the lateral width of each object between its widest width and its narrower width where the pin engages with the object.
In addition to the protrusions on the leading row former arm, an additional guide rail is added along one side of the row accumulating table surface. The guide rail extends along the side of the row accumulating table surface that is adjacent to the narrow width ends of the bottles at the ends of the rows. The guide rail is positioned perpendicular to the slot of the row former arms and is parallel to the direction of movement of the row former arms. The guide rail projects over the row accumulating table surface from the edge of the table surface to which it is attached. This positioning of the guide rail causes the object at the adjacent end of the row of objects moved across the accumulating table surface by the row former to engage with the guide rail and be tilted back slightly toward the center of the table and away from the table surface. In the preferred arrangement of rows of objects, the side of the objects arranged in rows having the smaller cross section width dimension will be positioned adjacent the guide rail, so the guide rail will be positioned on either side of the accumulating table surface so that it is adjacent the narrow width ends of the bottles. The tilting of the object at the end of each row adjacent the guide rail causes the bottom surface of the object adjacent the edge of the row accumulating table surface to be lifted from the surface, thereby decreasing the frictional engagement of the object at the end of the row with the accumulating table surface. This decreased frictional engagement of the object at the end of the row reduces forces tending to move or slightly rotate the object as the row of objects is pushed across the accumulating table surface. In this manner, the guide rail in combination with the plurality of protrusions on the leading arm of the row former prevent odd shaped objects arranged in a row from moving relative to each other as the row is moved across the surface of the row accumulating table in forming an array of the objects on the table.
By providing the overhanging guide rail and the leading arm of the pair of arms of the row former with a plurality of protrusions dimensioned and arranged as described above, the row former of the invention can move a row of irregularly shaped objects across the plane surface of the row accumulating table while preventing relative rotation or disorienting movement of the objects as they are moved across the table surface.